Passage 4.11.2
τῷ δὲ Ἀριστοδήμῳ καὶ τοῖς περὶ αὐτὸν διετάχθη τὰ ἐς τὴν μάχην οὕτως. ὅσοι τῶν Ἀρκάδων ἢ τῶν Μεσσηνίων τὰ μὲν σώματα ἦσαν ἐρρωμένοι καὶ ἀγαθοὶ τὰς ψυχάς, ὅπλα δὲ οὐκ εἶχον ἰσχυρά, τούτοις τῶν ὅπλων τὰ χρησιμώτατα ἐπέλεξε, καὶ ὡς τὸ ἔργον ἤπειγεν, ὁμοῦ τοῖς Ἀργείοις καὶ Σικυωνίοις καὶ τούτους ἔτασσε· τὴν δὲ φάλαγγα ἐπὶ πλέον ἥπλωσεν, ὡς μὴ κυκλωθεῖεν ὑπὸ τῶν ἐναντίων. προείδετο δὲ καὶ ὅπως τεταγμένοις σφίσι τὸ ὄρος ἡ Ἰθώμη κατὰ νώτου γίνοιτο. καὶ τούτοις μὲν Κλέοννιν ἐπέταξεν ἡγεμόνα·
The arrangements Aristodemus made for himself and his followers regarding the coming battle were thus: Those Arcadians and Messenians who were physically strong and courageous, but whose equipment was not effective, he selected for them the most useful arms available; and since the urgency of the task was pressing, he stationed these men together with the Argives and Sicyonians. He further extended the phalanx to avoid encirclement by the enemy. He also took precaution to position them so that Mount Ithome would lie at their backs. Over these troops he appointed Cleonnis as their commander.